Crystalline carbon fibers are known in the art. Examples of crystalline carbon include graphite, graphene, graphene oxide, non-fiber, non-particles, buckypaper, and pitch fibers. Pitch is a viscoelastic material that is composed of aromatic hydrocarbons, and is produced via the distillation of carbon-based materials, such as plants, crude oil, coal tar, and coal.
Crystalline carbon fibers have a high thermal conductivity in the axial direction. However, they have a much lower thermal conductivity in the radial direction. For example, pitch fibers may have a thermal conductivity of up to 900 W/m·K in the axial direction, but have a thermal conductivity as low as 30 W/m·K in the radial direction.